Significant differences exist in the risk factors men and women face for contracting human immunodeficiency virus (HIV), according to researchers at the Johns Hopkins Bloomberg School of Public Health who conducted a 10-year study of injection drug users living in Baltimore. For women, sexual activity is a greater risk factor for contracting HIV than the sharing of needles, visiting drug shooting galleries, or other aspects of the drug-related lifestyle. However, these same risk factors play a significant role among men for contracting HIV.

The findings, which appear in the May 28, 2001, edition of the Archives of Internal Medicine, suggest that HIV prevention efforts among drug users should be gender specific. "Injection drug use directly or indirectly accounts for nearly half of all of the people infected with HIV in the United States each year. Weve been very successful at reducing the spread of the disease with needle exchange programs, but our study shows we need more emphasis on preventing the high-risk sexual behaviors," says Steffanie Strathdee, PhD, lead author and associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

For the study, researchers analyzed data collected from 1,800 injection-drug users enrolled in the ALIVE (AIDS Link to Intravenous Experience) project. To be included, participants needed to be at least 18 years of age, have a history of injection drug use within the previous 10 years, and show no signs of HIV infection or AIDS at the beginning of the study. Between 1988 and 1998, researchers conducted semi-annual interviews with all of the study participants to collect information on drug use history and sexual behavior. Blood samples were taken to determine HIV infection.

Overall, Dr. Strathdee and her colleagues determined that high-risk sexual behavior was the greatest predictor for HIV infection for both male and female injection drug users. The study shows that men who also engaged in homosexual activity were four times more likely to contract HIV compared to men who did not report any homosexual activity. Women with a history of a recent sexually transmitted disease were twice as likely to become HIV-infected compared to women who did not. The risk of HIV infection was also twice as high for women who admitted having heterosexual relations with other injection drug users.

The researchers say needle sharing and visiting shooting galleries were also strong predictors of HIV infection among men; however, these risk factors were outweighed by sexual behavior among women. In addition, the researchers found that injection drug users under 30 years of age were twice as likely to become infected with HIV compared to those 40 and older, which was the only common predictor of infection for both men and women.

"We need a new approach to reach injection drug users and address the different risk factors between men and women. Some proposals might consider ways to educate and empower women to use condoms, especially the female condom that gives women more control. Others may consider counseling and education for couples to make both partners aware of the risks involved with drug use and sexual activity," explains Dr. Strathdee.